Question

A toy is made in the shape of a cylinder with one hemisphere stuck to one end

and a cone to the other end, as shown in the figure, the length of the cylindrical

part of the toy is 20cm and its diameter is 10cm. If the slant height of the cone

is 13cm. Find the surface area of the toy.​

Answer 1

Step-by-step explanation:

Let r cm be the radius and h cm the height of the cylindrical part. Then, r=5cm,h=13cm

Clearly radii of the spherical part and base of the conical part are also r cm. Let h

1

cm be the height, l cm be the slant height of the conical part.

Then

l

2

=r

2

+h

1

2

⇒l=

r

2

+h

1

2

⇒l=

5

2

+12

2

=13cm

Now

surface area of the toy=

curved surface area of the cylindrical part + curved surface area of hemispherical part + curved surface area of conical part

=(2πrh+2πr

2

+πrl)cm

2

=πr(2h+2r+l)cm

2

={

7

22

×5×(2×13+2×5+13)}cm

2

=770cm

Answer 2

Answer:

MARK ME AS BRILLIANT

Step-by-step explanation:

Let r cm be the radius and h cm the height of the cylindrical part. Then, r=5cm,h=13cm

Clearly radii of the spherical part and base of the conical part are also r cm. Let h1 cm be the height, l cm be the slant height of the conical part. 

Then

l2=r2+h12⇒l=r2+h12⇒l=52+122=13cm

Now 

surface area of the toy=

curved surface area of the cylindrical part +  curved surface area of hemispherical part + curved surface area of conical part

=(2πrh+2πr2+πrl)cm2

=πr(2h+2r+l)cm2

={722×5×(2×13+2×5+13)}cm2

=770cm2